Dilnessa, Yohannes
(2014)
*Production, Characterization and Optimization an of Stevia Sweetener from Stevia Leaf.*
Masters thesis, Addis Ababa University.

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## Abstract

Thisstudy has been carried out to extract the stevia sweetener, sugar substitute, from the leaf of stevia plant. Solvent extraction of the leaf using hot water was investigated. The main and interaction effects of temperature, extraction time and material ratio (stevia leaf: water) were examined. In the main effects investigation all the main factors had a significant effects on the yield of stevia sweetener. Butin the interaction effects, only temperature with material ratio and extraction time with material ratio had a significant effect on the yield of the sweetener. The interaction effects of temperature with extraction time (residence time) had no any significant effects on the yield of stevia sweetener. The two factor interaction model was developed. In this model the term which had no significant effects had been reduced. This term was the interaction effect of temperature with residence time (τβ) . Different analysis of the data such as analysis of the variance, hypothesis testing and predicted R-squared also enforce this idea. The p-value was ij 0.1270 which was greater than type one error 0.05. The F-calculate for this term was 1.74 that was less than F-tabulate 1.90. The predicted R-squared was 60.10% that was far from the adjusted R-squared 87.49%. These different analysis leads to the reduction of the interaction effect of temperature with residence time from the model. The model adequacy also investigated by normal probability plot of residuals and plot of residual verses predicted value. Both normal probability plot as well as residual verses predicted value plots showed that the model was acceptable. Optimum conditions for the extraction process were optimized. The optimal treatments of each factor to maximize the yield were, for the temperature 50 C, three hours for the extraction time and 1:10 material ratio. The maximum yield that was obtained at these optimum conditions was 49.90 %. The two methodsreport form and ramp form of optimization showed the same result or the same conditions. o

Item Type: | Thesis (Masters) |
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Uncontrolled Keywords: | Chemical and Bio Engineering |

Subjects: | Q Science > Q Science (General) Q Science > QD Chemistry T Technology > T Technology (General) T Technology > TP Chemical technology |

Divisions: | Africana |

Depositing User: | Andriamparany Edilbert RANOARIVONY |

Date Deposited: | 04 Oct 2018 08:37 |

Last Modified: | 04 Oct 2018 08:37 |

URI: | http://thesisbank.jhia.ac.ke/id/eprint/6693 |

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